U.S. manufacturing activity made gains in December with the pace picking up from the previous month, the Institute of Supply Management said Tuesday. The headline index (the Purchasing Managers\' Index) rose from 52.7 to 53.9, as manufacturing expanded for the 29th consecutive month, the institute said. Numbers above 50 indicate growth. Below 50 indicates a contraction. The institute said nine of 18 manufacturing groups showed growth in the month. The strongest growth in December was seen in apparel, leather and allied products, followed by textile mills, petroleum and coal, machinery and food and tobacco products. The component index for new orders rose from 56.7 to 57.6 in the month. The employment index climbed from 56.6 to 59.9, growing for the 27th consecutive month. The prices index moved lower, dropping from 48.3 to 47.1.